DDY391

DDY391 is a next-generation, clinical-stage **monoclonal antibody** developed by **Novartis** that targets the **CD40 ligand (CD40L)**, also known as **CD154**. It is currently being investigated for the treatment of **Sjögren's disease**, a chronic systemic autoimmune condition characterized by lymphocytic infiltration of exocrine glands. DDY391 works by binding to CD40L, thereby blocking its interaction with the CD40 receptor. This blockade disrupts the CD40-CD40L costimulatory pathway, which is critical for T-cell-dependent B-cell activation, germinal center formation, and the production of pathogenic autoantibodies. Unlike earlier anti-CD40L candidates that faced safety hurdles due to thromboembolic events (caused by Fc-mediated platelet activation), DDY391 is designed to avoid these issues, likely through Fc-engineering or silencing. The drug is administered via **subcutaneous** injection and is currently in **Phase 2** clinical development.